TECHNOLOGY

Technology

The sensor and platform behind the data.

Magnetometer: QuSpin QTFM Gen-2

Our magnetic surveys are built around the QuSpin QTFM Gen-2, a pulsed, rubidium optically pumped magnetometer. It is a second-generation sensor designed for integration into compact unmanned aerial and underwater platforms, with a substantial gain in robustness over the earlier G1.

Two design features matter most in the field. It holds sensitivity and stability in noisy, rapidly changing magnetic environments, tolerating fast field changes without losing lock. And its deadzone is a negligible axial cone rather than the large planar deadzone of earlier sensors, so it operates cleanly across a wide range of orientations and latitudes.

The sensor is inherently a total-field (scalar) instrument. An optional three-axis coil attachment slides over the sensor head and applies known bias fields, from which the vector components of the background field are calculated. We use this vector capability for heading-error compensation via Tolles-Lawson modelling, not simply as a different deliverable.

The QuSpin QTFM Gen-2 total-field quantum magnetometer, sensor head and electronics control unit — The QuSpin QTFM Gen-2 scalar quantum magnetometer.

Specifications

Manufacturer's published specifications for the QTFM Gen-2. Figures vary by sensor version, firmware and configuration.

MEASUREMENT PERFORMANCE

Magnetometer type	Pulsed rubidium total-field
Measurement method	Free induction decay
Scalar sensitivity	<5 pT/√Hz (typ. 3 pT/√Hz)
Derived-vector sensitivity	<0.1 nT/√Hz, optional
Output data rate	Scalar ≤1000 Hz; triaxial ≤250 Hz
Bandwidth	Up to 500 Hz
Operating range	1,000–150,000 nT typ.
Heading error	<3 nT, uncompensated
Dead zone	Axial cone, <±7° (typ. <5°)
Slew rate limit	None
Maximum field gradient	Approximately 300 nT/cm
Operating temperature	−15 to +55 °C

PHYSICAL

Sensor head	17.7 × 19.8 × 35.8 mm
Electronics control unit	14.7 × 24.4 × 92.3 mm
Weight	12 g sensor head + 29 g ECU (6.5 g without housing)

ELECTRICAL & COMMUNICATION

Input power	+5 V via Standard Comms Board, or 10–12 V
Operating power	Approximately 2.5 W
Startup power	Approximately 3.5 W
Digital communication	UART; USB via Standard Comms Board
Filtering	Programmable onboard digital filtering
Calibration	None required

The QTFM has been independently deployed and tested in peer-reviewed UAV magnetic research, including a Technical University of Denmark study on sensor choice and bird design for kilometre-scale UAV surveying, and a Université Clermont Auvergne study validating drone magnetic surveying for volcano monitoring against ground data. It is a sensor with a track record in published geophysical work.

References:

Towed bird

The magnetometer never flies on the airframe. It rides in a custom towed bird well below the aircraft, which keeps the sensor away from the platform's motors, ESCs and batteries, the dominant noise sources in close-mounted setups. The bridle geometry constrains the bird's motion in flight, so the sensor tracks stably and any residual heading behaviour is consistent and correctable in processing rather than random.

The QuSpin magnetometer bird in flight, towed below the drone on a long line — The magnetometer bird in flight, towed well below the aircraft.

The drone in flight towing the magnetometer bird on a long line below it — In survey flight: the sensor tracks well below and behind the drone.

Platform: DJI Matrice 300 RTK

We fly the DJI Matrice 300 RTK. Long flight times and features such as obstacle avoidance make it well suited to surveying large areas per sortie, and its rugged, IP45-rated build lets us operate reliably in the conditions of the Australian outback. It is an industry-standard platform for this work.

The DJI Matrice 300 RTK survey drone — The DJI Matrice 300 RTK, our survey platform.

Talk to us about your project

Send us the tenement outline or site boundary and the deliverables you need. We will come back with a fixed, itemised quote, usually within two business days.

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